1. Field of the Invention
The present invention relates to a Tower Type Heat Sink having a structure in which a heat radiating fins are mounted on a heat transferring portion erected on a base portion.
2. Related Art
In general, heat sinks have a function to enlarge substantial heat radiating area of an exothermic member or a hot section by means of contacting with such exothermic member or hot section. Accordingly, it is sufficient for this kind of heat sinks only to be provided with fins for composing a heat radiating face as many as possible. Also, heat sinks structured with fins arranged on its base member in order to have flexibility for cooling objects are used in a general way. However, there is a disadvantage on the heat sinks having such structure due to difficulty of mounting a number of thin plate shaped heat radiating fins on its base member, namely, the actual heat radiating area of those is limited.
On the other hand, there is an advantage on a tower type heat sink which is structured with erecting a heat transferring member such as braces on its base portion and mounting heat radiating fins on such a heat transferring member, that is, the limitation of mounting numbers of heat radiating fins and the limitation of heat radiating area is reduced, because of its availability of mounting heat radiating fins in consequence of fitting those fins into the heat transferring member and the like. An example of this kind of tower type heat sink is disclosed in U.S. Pat. No. 5,412,535, and this heat sink employs a heat pipe or a vapor chamber as said heat transferring member. Namely, a hollow container is erected on the base member and inside of it is employed as a heat pipe, and meanwhile, a plurality of fins is fitted on the outer face of the container.
In the above mentioned heat pipe in the prior art, heat resistance on the part from the base member to the heat radiating fins may be reduced, because the trapezoidal heat pipe or the vapor chamber mediates heat transfer from the base portion to the fins, and furthermore, the heat transfer is executed by a latent heat of a working fluid. In the tower type heat sink having such structure, the heat pipe with fins mounted thereon has to also have a function as a brace for a plurality of fins to be mounted; therefore, the heat pipe and the base member must be fixed integrally. Consequently, there is a disadvantage in productivity due to the complexity of its fixing structure between the heat pipe and the base member.
Moreover, in the tower type heat sink as described hereinbefore, it is necessary to form so-called fixing part, in which fins are not mounted on a part of said heat pipe in order to fix the heat pipe onto the base member. A portion of this fixing part is exposed in the vicinity of the face of the base member unavoidably, as the heat sink is assembled. This fixing portion is a portion for fixing the heat pipe onto the base member, and also is a portion for transferring a heat to the heat radiating member of the heat sink wherein fins are mounted thereon. Accordingly, the fixing part is not a portion to radiate a heat positively, and it is preferable to have a temperature difference against the heat radiating member in order to transfer a heat efficiently from the heating portion to the heat radiating member.
However, in case of sending air to said tower type heat sink by a fan or the like for compulsory cooling purpose, the air stream towards not only the heat radiating member, but also the fixing part exposed from said base portion preferentially. Because, resistance of fluidity of the fins at the heat radiating member is higher than the resistance of fluidity at the fixing part. In consequence, heat transfer cannot be executed efficiently and cooling performance of the tower type heat sink is deteriorated disadvantageously.